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<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="zend.view.abstract"></a>48.5. Zend_View_Abstract</h2></div></div></div>
<p>
        <code class="code">Zend_View_Abstract</code> is the base class on which
        <code class="code">Zend_View</code> is built; <code class="code">Zend_View</code> itself simply
        extends it and declares a concrete implementation of the
        <code class="code">_run()</code> method (which is invoked by <code class="code">render()</code>).
    </p>
<p>
        Many developers find that they want to extend
        <code class="code">Zend_View_Abstract</code> to add custom functionality, and
        inevitably run into issues with its design, which includes a number of
        private members. This document aims to explain the decision behind the
        design.
    </p>
<p>
        <code class="code">Zend_View</code> is something of an anti-templating engine in that
        it uses PHP natively for its templating. As a result, all of PHP is
        available, and view scripts inherit the scope of their calling object.
    </p>
<p>
        It is this latter point that is salient to the design decisions.
        Internally, <code class="code">Zend_View::_run()</code> does the following:
    </p>
<pre class="programlisting">&lt;?php
protected function _run()
{
    include func_get_arg(0);
}
?&gt;</pre>
<p>
        As such, the view scripts have access to the current object
        (<code class="code">$this</code>), <span class="emphasis"><em>and any methods or members of that
            object</em></span>. Since many operations depend on members with
        limited visibility, this poses a problem: the view scripts could
        potentially make calls to such methods or modify critical properties
        directly. Imagine a script overwriting <code class="code">$_path</code> or
        <code class="code">$_file</code> inadvertently -- any further calls to
        <code class="code">render()</code> or view helpers would break!
    </p>
<p>
        Fortunately, PHP 5 has an answer to this with its visibility
        declarations: private members are not accessible by objects extending a
        given class. This led to the current design: since
        <code class="code">Zend_View</code> <span class="emphasis"><em>extends</em></span>
        <code class="code">Zend_View_Abstract</code>, view scripts are thus limited to only
        protected or public methods and members of
        <code class="code">Zend_View_Abstract</code> -- effectively limiting the actions it
        can perform, and allowing us to secure critical areas from abuse by view
        scripts.
    </p>
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